In a rugged canyon of southeast Arizona, several dozen people are in the middle of a three-year silent retreat. They live in rustic cabins at Diamond Mountain University, which bills itself as a Buddhist-based education and retreat center. The retreatants have no electricity or electronic devices. Most of them are practicing Buddhists and reportedly spend their time in meditation and study.

PHOTO: Mark Duggan
A stupa, or Buddhist religious monument, at Diamond Mountain.

Their needs are attended to by a group of volunteers. They deliver food and medical attention to the retreatants, but otherwise maintain little contact with them. But they say they're getting their own form of spiritual fulfillment by working with the retreatants, albeit on a silent level.

PHOTO: Mark Duggan
Bulk food is stored in bins at the Diamond Mountain commissary.

Producer Mark Duggan met with some of the volunteers to hear their stories. They paused from packing up food for the retreatants to talk about their own experiences in silent retreats, and what volunteering to help with this retreat does for them.

PHOTO: Mark Duggan
Scott Vasek checks food boxes before starting a delivery run to the retreatants.

Extended vows of silence, or monastic silence, exist across many spiritual traditions, from Christianity to Buddhism to Hinduism. It's commonly believed that silence draws a person closer to divinity. Some scientific evidence even suggests that it can change a person's consciousness.

Web extra interview: Mark Duggan talks with Al Kaszniak, Ph.D., head of the department of psychology at the University of Arizona, about meditation's effects on consciousness.

Web extra interview: An interview with Geshe Michael Roach, a sometimes controversial Buddhist monk who founded Diamond Mountain. This interview focuses on his experiences participating in lengthy silent meditations.